Multiple pipette and method of using the same

ABSTRACT

A multiple pipette X according to the present invention includes a first pipette  1  and a second pipette  2.  The first pipette  1  is capable of dispensing a liquid stored in a liquid storing section  17   a  divisionally a plurality of times each by a constant amount. The second pipette  2  is capable of dispensing a liquid sucked from the outside all at a time. The first pipette utilizes, for example, a ratchet mechanism  12   d,    13   a  for dispensing the liquid divisionally a plurality of times each by a constant amount. Preferably, the first pipette  1  is provided with a cap  19  removably attached to the tip end thereof.

TECHNICAL FIELD

[0001] The present invention relates to a multiple pipette having aplurality of pipettes and a method of using the same. Such multiplepipettes include ones for dispensing plural kinds of liquids separatelyand others for mixing plural kinds of liquids or diluting a targetliquid for dispensing the mixed liquid or the diluted liquid.

BACKGROUND ART

[0002] For measuring the concentration of a particular component in asample liquid, there exists a method in which the sample liquidcontaining an unknown concentration of the particular component and areference liquid containing a known concentration of the particularcomponent are bridged for measuring a potential difference generatedtherebetween to thereby compute the concentration of the particularcomponent from the measured potential difference.

[0003] In this method, a concentration measuring plate is set, forexample, to an analyzing apparatus for determining the concentration ofthe particular component.

[0004] The analyzing apparatus includes at least a set section forsetting the plate, two probes, and computation means for computing theconcentration of the particular component from the potential differencebetween the probes.

[0005] The plate includes at least a first liquid receiving portion towhich a reference liquid is applied, a first terminal for conductionwith the reference liquid applied to the first liquid receiving portion,a second liquid receiving portion to which a sample liquid is applied, asecond terminal for conduction with the sample liquid applied to thesecond liquid receiving portion, and a bridge for shorting between thereference liquid in the first liquid receiving portion and the sampleliquid in the second liquid receiving portion.

[0006] When the plate is set to the set section of the analyzingapparatus, the probes of the analyzing apparatus come into contact withthe first terminal and the second terminal for measuring the potentialdifference between the reference liquid and the sample liquid. Thecomputation means computes the concentration of the particular componentof the sample liquid based on the measured potential difference.

[0007] A double pipette may be used for applying the reference liquid tothe first liquid receiving portion and for applying the sample liquid tothe second liquid receiving portion of the plate. For example, use maybemade of such a double pipette that includes a first pipette for drawingand dispensing the reference liquid through a liquid dispensing orificeand a second pipette for drawing and dispensing the sample liquidthrough a liquid dispensing orifice. The first pipette and the secondpipette are held in a casing for example so that the distance betweenrespective liquid dispensing orifices corresponds to the distancebetween the first liquid receiving portion and the second liquidreceiving portion of the plate. The liquid dispensing orifice of eachpipette may be an opening of a tip attached to the tip end of thepipette.

[0008] The double pipette may have the following problems when thereference liquid previously drawn in remains in the tip. Firstly, theamount of dispensing fluctuates when the remaining reference liquid isdispensed together with the reference liquid later drawn in. Suchfluctuation of the dispensing amount also occurs when the first pipettecannot draw a liquid by a constant amount. Secondly, when the drawingand dispensing of a reference liquid is performed after a long intervalfrom the previous drawing and dispensing of the reference liquid, thereference liquid remaining in the tip as adhered to the inner surfaceconcentrates. The mixing of the concentrated liquid into the latersucked reference liquid causes the concentration of the reference liquidto vary.

[0009] When a sample liquid previously drawn in remains in the tip, thefollowing problems may occur. Since the concentrations of a particularcomponent may differ between the sample liquids to be measured, when theremaining sample liquid is mixed in a sample liquid to be measured next,the concentration of the sample liquid may vary.

[0010] Therefore, in the prior art double pipette, the tip of eachpipette is replaced every time the reference liquid or the sample liquidis dispensed for avoiding the influence of the reference liquid orsample liquid previously drawn in and dispensed. However, this causesthe following problems.

[0011] Firstly, since a large number of tips need be used, the pipetteis disadvantageous in terms of the cost. The number of tips disposed of(as waste) is correspondingly large. Secondly, although the samereference liquid is used for plural measurements, the reference liquidneed be drawn in each time of the measurements. Therefore, the drawingwork is troublesome when a large number of sample liquids need bemeasured.

[0012] Moreover, even when a tip is replaced every time of the drawingand dispensing of the liquid, the problem of the sucking amountfluctuation is not solved. Therefore, it is still impossible to dispensethe liquid by a fixed amount.

DISCLOSURE OF THE INVENTION

[0013] According to a first aspect of the present invention, there isprovided a multiple pipette which includes a first pipette fordispensing a liquid stored in a liquid storing section divisionally aplurality of times each by a constant amount, and a second pipette fordispensing a liquid drawn from the outside all at a time.

[0014] In a preferred embodiment, the first pipette includes a pistonrod for pushing out the liquid from the liquid storing section, and acylinder accommodating the piston rod at least partially. The piston rodis formed with a plurality of successive ratchet grooves, whereas thecylinder is provided with a pawl for engagement with the plurality ofratchet grooves. The cylinder is movable in a first direction togetherwith the piston rod with the pawl engaged in the ratchet groove and ismovable in a second direction opposite the first direction separatelyfrom the piston rod.

[0015] In a preferred embodiment, the piston rod is provided with anoperation knob, which is movable for moving the piston rod separatelyfrom the cylinder. Moving the operation knob in the first directioncauses a gas in the liquid storing section to be discharged, whereasmoving the operation knob in the second direction causes a liquid to bedrawn into the liquid storing section.

[0016] In a preferred embodiment, the first pipette incorporates a slidepiece for supporting the pawl. The pawl is held on the slide piece whenthe piston rod is moved by the operation knob.

[0017] In a preferred embodiment, the first pipette includes a pistonrod for pushing out the liquid from the liquid storing section, and ahousing accommodating the piston rod. The liquid storing section isdefined by a syringe having an inner space, and the syringe isthreadedly attached to the housing.

[0018] In a preferred embodiment, the first pipette includes a nozzleconnected to the liquid storing section. The nozzle includes adispensing orifice for dispensing the liquid in the liquid storingsection to the outside.

[0019] The first pipette may include a cap removably attached forcovering the dispensing orifice. The nozzle may be protected by areinforcing portion.

[0020] According to a second aspect of the present invention, there isprovided a method of using a multiple pipette which comprises a firstpipette for dispensing a first liquid stored in a liquid storing sectiondivisionally a plurality of times each by a constant amount, and asecond pipette for dispensing a second liquid drawn from the outside allat a time. The first liquid may be a reference liquid containing a knownconcentration of a particular component, whereas the second liquid maybe a sample liquid containing an unknown concentration of a particularcomponent.

[0021] According to a third aspect of the present invention, there isprovided a multiple pipette which comprises a first pipette fordispensing a first liquid stored in a liquid storing sectiondivisionally a plurality of times each by a constant amount, and asecond pipette for dispensing a second liquid drawn from the outside allat a time. The first liquid may be mixed with the second liquid or thesecond liquid may be diluted with the first liquid.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a sectional view illustrating an example of multiplepipette according to the present invention.

[0023]FIG. 2 is an enlarged view illustrating a principal part of thefirst pipette constituting the multiple pipette of FIG. 1.

[0024]FIG. 3 is an exploded perspective view illustrating a potentialdifference measuring plate.

[0025]FIG. 4 is an enlarged view of a principal portion in a state wherea reference liquid and a sample liquid are applied to the potentialdifference measuring plate of FIG. 3 using the multiple pipette of FIG.1.

BEST MODE FOR CARRYING OUT THE INVENTION

[0026] As shown in FIG. 1, a multiple pipette X includes a first pipette1 and a second pipette 2. The first pipette 1 and the second pipette 2are held in a casing 3.

[0027] The first pipette 1 includes a housing 10, a piston rod 11 and acylinder 12. The piston rod 11 is held in the housing 1 with the upperend portion thereof received in the cylinder 12.

[0028] The piston rod 11 has a rod section 13 and a plug 14. The rodsection 13 has an upper end portion to which an operation knob 13 c isattached via an outwardly projecting pin 13 b. As clearly shown in FIG.2, the rod section 13 has a mid-portion formed with a plurality ofsuccessive ratchet grooves 13 a.

[0029] As shown in FIG. 1, the cylinder 21 is formed, at the upper endportion thereof, with an engagement portion 12 a which is larger indiameter than other portions. The cylinder 12 has a circumferential wall12 b formed with a slit 12 c. The slit 12 c extends longitudinally ofthe cylinder 12 for allowing the vertical movement of the pin 13 b. Thecircumferential wall 12 b has a lower end portion to which a pawl 12 dis pivotally attached. As clearly shown in FIG. 2, the pawl 12 d is inthe form of a crank. The tip end of the pawl 12 d is configuredcorrespondingly to the configuration of the ratchet grooves 13 a. Thoughnot clearly shown in the figure, the pawl 12 d is biased toward thepiston rod 11 by a torsion coil spring for example. Therefore, when thepawl 12 d moves downward, the pawl 12 d engages the ratchet groove 13 a,thereby moving the piston rod 11 downward together. On the other hand,when the pawl 12 d moves upward, the pawl 12 d does not engage theratchet groove 13 a so that the pawl 12 d moves separately from thepiston rod 11.

[0030] As shown in FIG. 1, the housing 10 has an upper opening 10 a anda lower opening 10 b.

[0031] A rod section 15 a of a push rod 15 is inserted in the upperopening 10 a. The push rod 15 has a plug 15 b accommodated in thehousing 10 in close contact with the upper surface of the cylinder 12.The rod section 15 a has an upper end to which an operating portion 15 cis attached. An engagement portion 10 e is provided in the housing 10. Acoil spring 16 is disposed between the engagement portion 10 e and theengagement portion 12 a of the cylinder 12. The coil spring 16 surroundsthe upper end portion of the cylinder 12. Thus, the cylinder 12 and thepush rod 15 are biased in the upward direction in FIG. 1.

[0032] A syringe 17 is threadedly fitted into the lower opening 10 b ofthe housing 10. The syringe 17 includes a liquid storing section 17 a towhich a nozzle 17 bis threadedly fitted. Thus, the syringe 17 isremovable from the housing 10. The liquid storing section 17 a isremovable from the syringe 17. When removed, the liquid storing section17 a can be easily washed.

[0033] The nozzle 17 b is in the form of a thin tube at portions exceptfor the portion threadedly fitted to the liquid storing section 17 a, sothat a liquid retained in the liquid storing section 17 a can bedirectly dispensed from the nozzle 17 b. Therefore, the first pipette 1does not require the use of tips. Therefore, the number of tips used bythe multiple pipette can be reduced, which leads to reduction in costand waste.

[0034] The tubular portion of the nozzle 17 b is protected by areinforcing portion 17 c except for the tip end of the nozzle. A cap 19for covering the tip end of the nozzle 17 b is removably attached to thereinforcing portion 17 c. Preferably, the cap 19 is attached so that thetip end of the nozzle 17 c is held in close contact with the innerbottom surface of the cap.

[0035] The nozzle 17 b is likely to be bent because of its thin tubularconfiguration. However, the provision of the reinforcing portion 17 cprevents the nozzle 17 b from being damaged. Further, the cap 19 can beeasily attached owing to the provision of the reinforcing portion.

[0036] The attaching of the cap 19 to the nozzle 17 b prevents theevaporation of the liquid retained in the liquid storing section 17 a.Therefore, it is possible to prevent a particular component fromconcentrating due to the evaporation of water for example, so that theconcentration of the liquid to be dispensed is kept unchanged for a longtime.

[0037] As clearly shown in FIG. 2, a slide piece 18 is provided in thehousing 10. The slide piece 18 is provided over the ratchet grooves 13a. In a normal state, the pawl 12 d is held on the slide piece 18. Whilethe pawl 12 d moves downward for a distance corresponding to the width(the dimension in the vertical direction of FIG. 1) of the slide piece18, the pawl 12 d moves on the slide piece 18. When the pawl 12 d movesdownward for a distance exceeding the width of the slide piece, the pawl12 d drops from the slide piece 18 into engagement with the ratchetgroove 13 a. As described above, when the pawl 12 d moves downward inthe engaged state, the piston rod 11 d moves downward together with thepawl 12 d. When the pawl 12 d moves upward, the pawl 12 d moves asseparated from the piston rod 11.

[0038] The housing 10 has a side wall 10 c formed with a window 10 d forallowing the vertical movement of the pin 13 b. The plug 14 of thepiston rod 11 is arranged in the liquid storing section 17 b as closelyfitted therein. Thus, when the pawl 12 d is held on the slide piece 18,the vertical movement of the operation knob 13 c makes the piston rod 11move vertically within the housing 10 and the liquid storing section 17b.

[0039] In the first pipette 1, liquid is retained in the liquid storingsection 17 a in the following manner.

[0040] First, with the cap 19 removed, the operation knob 13 c is moveddownward to lower the piston rod 11, thereby discharging the gas fromthe liquid storing section 17 a. Subsequently, with the operation knob13 c kept lowered, the tip end of the nozzle 17 b is placed in liquid tobe drawn. Then, the operation knob 13 c is moved upward to raise thepiston rod 11, thereby drawing the liquid into the liquid storingsection 17 a.

[0041] The liquid in the liquid storing section 17 a is dispensed asfollows. First, the operating portion 15 c of the push rod 15 is moveddownward to lower the cylinder 12 and the pawl 12 d. As clearly shown inFIG. 2, since the pawl 12 d is held on the slide piece 18 in the normalstate, the pawl 12 d moves downward on the slide piece 18 in accordancewith the downward movement of the push rod 15. When the pawl 12 d isfurther moved downward, the pawl 12 d drops from the slide piece 18 intoengagement with the ratchet groove 13 a. When the push rod 15 is furtherlowered, the piston rod 11 moves downward together with the pawl 12 d.As a result, the liquid in the liquid storing section 17 a is pusheddownward for dispensing from the tip end of the nozzle 17 b by an amountin accordance with the amount of movement of the piston rod 11.

[0042] For dispensing a constant amount of liquid in each time of theoperation, the stroke of the piston rod 11 in each time of the operationneeds to be fixed. For this purpose, the stroke of the piston rod 11 isset equal to one pitch of the ratchet grooves 13 a or to an integralmultiple of one pitch. Accordingly, the stroke of the push rod 15 is thevalue obtained by adding the one pitch or an integral multiple of theone pitch of the ratchet grooves 13 a to the movement distance of thepawl from the state held on the slide piece 18 until it comes intoengagement with the ratchet groove 13 a.

[0043] When the force applied to the operating portion 15 c is releasedafter the dispensing of liquid from the first pipette 1, the cylinder12, the push rod 15 and the pawl 12 d move upward due to the biasingforce of the coil spring 16. At this time, the pawl 12 d disengages fromthe ratchet groove 13 a and moves upward again on the slide piece 18 tobe held at its original position.

[0044] With the multiple pipette X, repeating of the operation oflowering the piston rod 11 by the exertion of a force to the operatingportion 15 c and then releasing the force enables repetitive dispensingof the liquid by a constant amount. Therefore, fluctuations ofdispensing amount of liquid due to fluctuations of drawing amount ofliquid can be avoided.

[0045] The second pipette 2 includes a housing 20, a piston rod 21 andan intermediate rod 22. The piston rod 21 and the intermediate rod 22are accommodated in the housing 20.

[0046] The housing 20 includes a housing body 20A and a nozzle section20B. The nozzle section is formed with a tip end opening 20 a whichprovides communication between the inside and outside of the housing 20.The housing body 20A is formed, at the lower position and the middleposition thereof, with engagement portions 20 b, 20 b projectinginwardly toward the center.

[0047] The piston rod 21 includes a rod section 21 a and a plug 21. Theplug 21 is accommodated in the housing body 20A. The rod section 21 a isaccommodated partially in the housing body 20A and partially in thenozzle section 20B. A coil spring 24 is disposed between the plug 21 band the engagement portion 20 b of the housing body 20A. The coil spring24 surrounds the upper end portion of the rod section 21 a. The coilspring 24 biases the piston rod 21 in the upper direction in FIG. 1.

[0048] The intermediate rod 22 includes a rod section 22 a and a plug 22b. The plug 22 b is held in close contact with the plug 21 b of thepiston rod 21. Therefore, the intermediate rod 22 is also biased in theupper direction in FIG. 1.

[0049] The housing 22 has an upper surface formed with an opening 20 a.A rod section 23 a of a push rod 23 is inserted in the opening 20 a. Thepush rod 23 is provided with a plug 23 b, which is accommodated in thehousing 20 as kept in close contact with the upper end of theintermediate rod 22. The rod section 23 a has an upper end to which anoperating portion 23 c is attached. A coil spring 25 is disposed betweenthe lower surface of the plug 23 b and the engagement portion 20 c ofthe housing body 20A. The coil spring 25 surrounds an upper portion ofthe intermediate rod 22. The coil spring 25 biases the pushing rod 23upward.

[0050] With the second pipette 2, the drawing and dispensing of liquidis performed as follows.

[0051] First, a tip 26 is attached to the tip end of the nozzle section20B. Subsequently, a force is exerted to the operating portion 23 c ofthe push rod 23 to move the piston rod 21 and the intermediate rod 22downward. Then, with the tip 26 placed in a sample liquid contained in avial or a test tube, the force exerted to the push rod 23 is released.As a result, the piston rod 21, the intermediate rod 22 and the push rod23 biased by the springs 24, 25 move upward to draw the liquid into thetip 26. For example, 20 μl of sample liquid is drawn.

[0052] The dispensing of the liquid is performed by moving the push rod23 downward to push out the liquid from the tip 26. When the forceapplied to the push rod 23 is released, the push rod 23 returns to itsoriginal state due to the biasing force of the coil springs 24, 25.

[0053] The multiple pipette X is capable of dispensing two kinds ofliquid. For example, a reference liquid containing a known concentrationand a sample liquid containing an unknown concentration may bedispensed. Therefore, as shown in FIG. 4, the multiple pipette X may beused for simultaneously supplying a reference liquid and a sample liquidto a potential difference measuring plate 4 as shown in FIG. 3.

[0054] The potential difference measuring plate 4 is used for measuringa potential difference between a reference liquid and a sample liquidwith an analyzing apparatus (not shown). In the analyzing apparatus, theconcentration of a particular component of the sample liquid is computedin accordance with the measured potential difference.

[0055] As clearly shown in FIG. 3, the potential difference measuringplate 4 includes a base film layer 40 on which a resist layer 41 and acover film layer 42 are laminated. The potential difference measuringplate 4 measures the potential difference with respect to three kinds ofions such as Na⁺, Ka⁺ and Cl⁻, for example.

[0056] The base film layer 40 has insulating properties. The base filmlayer 40 has an elongated rectangular configuration as a whole.

[0057] The base film layer 40 has an opposite pair of end edgesrespectively formed with three terminals 40A-40C and three terminals40D-40F. The three terminals 40A-40C, 40D-40F are aligned widthwise ofthe base film layer 40. As will be described later, each of theterminals 40A-40F is brought into contact with a probe for measuring thepotential difference.

[0058] The base film layer 40 is centrally formed with six liquidreceiving pads 40 a-40 f. The liquid receiving pads 40 a-40 f areprovided for receiving particular components of reference liquid orsample liquid. The liquid receiving pads 40 a-40 f are electricallyconnected to the terminals 40A-40F via conductive wires 40Aa, 40Bb,40Cc, 40Dd, 40Ee and 40Ff, respectively.

[0059] The resist film layer 41 comprises a first resist film layer 43and a second resist film layer 44. The first resist film layer 43 andthe second resist film layer 44 have insulating properties. Each of thefirst resist film layer 43 and the second resist film layer 44 has anelongated rectangular configuration as a whole.

[0060] The resist film 41 has an opposite pair of end edges respectivelyformed with three insertion holes 41A-41C and three insertion holes41D-41F. The insertion holes 41A-41F are provided at locationscorresponding to the terminals 40A-40F of the base film layer 40. Eachof the insertion holes 41A-41F is made up of a corresponding one ofthrough-holes 43A-43F formed in the first resist film layer 43 and acorresponding one of through-holes 44A-44F formed in the second resistfilm layer 44. The terminals 40A-40F are exposed through thethrough-holes 41A-41F, respectively.

[0061] The second resist film layer 44 is centrally formed with sixcommunication holes 44 a-44 f. The communication holes 44 a-44 f arerespectively provided with ion selection membranes 45 a-45 f fittedtherein. For example, the ion selection membranes 45 a, 45 d selectivelypass Na⁺, the ion selection membranes 45 b, 45 e selectively pass K⁺,and the ion selection membranes 45 c, 45 f selectively pass Cl⁻.

[0062] The first resist film 43 is centrally formed with a referenceliquid retaining opening 43 g and a sample liquid retaining opening 43h. The reference liquid retaining opening 43 g communicates with thethree communication holes 44 a, 44 b, 44 c. The sample liquid retainingopening 43 h communicates with the three communication holes 44 d, 44 e,44 f. The reference liquid retaining opening 43 g communicates with thereference liquid retaining opening 43 h through a cutout 43 i. A bridge45 i for allowing the movement of ions is disposed in the cutout 43 i.

[0063] The cover film layer 42 has an opposite pair of end edgesrespectively formed with three insertion holes 42A-42C and threeinsertion holes 42D-42F. The insertion holes 42A-42F communicate withthe insertion holes 41A-41F of the resist film layer 41, respectively.Therefore, the terminals 40A-40F of the base film layer 40 are exposedthrough the relevant insertion holes 41A-41F.

[0064] The cover film layer 42 has an opposite pair of longitudinaledges which are centrally formed with a reference liquid receiving hole42 g and a sample liquid receiving hole 42 h, respectively. Thereference liquid receiving hole 42 g communicates with the referenceliquid retaining opening 43 g of the first resist film layer 43. Thesample liquid receiving hole 42 h communicates with the sample liquidretaining opening 43 h of the first resist film layer 43. The cover filmlayer 42 is further formed with insertion holes 42B, 42E and two airvents 42 j provided adjacent to the insertion openings. Each of theairvents 42 j communicates with both the reference liquid retainingopening 43 g and the sample liquid retaining opening 43 h.

[0065] For applying a reference liquid R and a sample liquid S to thepotential difference measuring plate 4, the tip end of the nozzle 17 bof the first pipette 1 is positioned at the reference liquid receivinghole 42 g, whereas the tip end of the tip 26 attached to the secondpipette 2 is positioned at the sample liquid receiving hole 42 h. Then,respective operating portions 15 c, 23 c of the push rods 15, 23 of thepipettes 1, 2 are moved downward. As a result, a predetermined amount ofreference liquid R is dispensed from the first pipette 1 and thereference liquid R is applied to the plate through the reference liquidreceiving hole 42 g. Form the second pipette 2, a predetermined amountof sample liquid S is dispensed and applied to the plate through thesample liquid receiving hole 42 h.

[0066] The reference liquid applied through the reference liquidreceiving hole 42 g is retained in the reference liquid retainingopening 43 g, whereas the sample liquid S applied through the sampleliquid receiving hole 42 h is retained in the sample liquid retainingopening 43 h. Since the reference liquid retaining opening 43 g isconnected to the sample liquid receiving hole 42 h via the cutout 43 iprovided with the bridge 45 i, the reference liquid R and the sampleliquid S are short-circuited.

[0067] The Na⁺, Ka⁺, Cl⁻ ions in the reference liquid R retained in thereference liquid retaining opening 43 g pass through the relevant ionselection membranes 45 a, 45 b, 45 c to reach the reference liquidreceiving pads 40 a, 40 b, 40 c. The Na⁺, Ka⁺, Cl⁻ ions in the sampleliquid S retained in the sample liquid retaining opening 43 h passthrough the relevant ion selection membranes 45 d, 45 e, 45 f to reachthe sample liquid receiving pads 40 d, 40 e, 40 f. As a result,potential differences are generated between the reference liquidreceiving pads 40 a, 40 b, 40 c and the sample liquid receiving pads 40d, 40 e, 40 f, respectively, due to the concentration difference of Na⁺,Ka⁺ or Cl⁻ between the reference liquid R and the sample liquid S.

[0068] The potential differences are measured by potential differencemeasurement means (not shown) having six probes P₁-P₆. The potentialdifference due to the Na⁺ concentration difference is measured bybringing probes P₁, P₂ into contact with the terminals 40A, 40D. Thepotential difference due to the K⁺ concentration difference is measuredby bringing probes P₃, P₄ into contact with the terminals 40B, 40E. Thepotential difference due to the Cl⁻ concentration difference is measuredby bringing probes P₅, P₆ into contact with the terminals 40C, 40F.

[0069] The concentration of each ion can be determined from the measuredpotential based on a calibration curve prepared in advance, for example.

[0070] With the multiple pipette X, the reference liquid R in the liquidstoring section 17 a can be dispensed as divided into a plurality oftimes each by a constant amount. Therefore, even in the case where theconcentration measurement of a particular component is performed withrespect to a plurality of sample liquids S, the drawing of the referenceliquid R into the first pipette 1 need not be performed for each sampleliquid R to be measured. The attachment and removal of the tip 26relative to the first pipette 1 is also unnecessary. Therefore, theoperation efficiency in applying the reference liquid R and the sampleliquid S is enhanced. Since the first pipette 1 does not require tips,the total number of tips used by the multiple pipette X decreases, whichleads to the reduction in cost and amount of the resulting waste.

[0071] In the multiple pipette according to the present invention, whenthe amount of liquid in the liquid storing section becomes insufficient,the liquid storing section may be replaced with another one containingsufficient reference liquid.

[0072] The multiple pipette according to the present invention may beused for mixing plural kinds of liquids or diluting a target liquid. Inthis case, respective liquid dispensing orifices of the first and thesecond pipettes may be made close to each other or combined with eachother for mixing or diluting the liquids.

[0073] The multiple pipette according to the present invention mayinclude three or more pipettes.

1. A multiple pipette comprising: a first pipette for dispensing aliquid stored in a liquid storing section divisionally a plurality oftimes each by a constant amount; and a second pipette for dispensing aliquid drawn from outside all at a time.
 2. The multiple pipetteaccording to claim 1, wherein the first pipette includes a piston rodfor pushing out the liquid from the liquid storing section, and acylinder accommodating the piston rod at least partially; the piston rodbeing formed with a plurality of successive ratchet grooves; thecylinder being provided with a pawl for engagement with the plurality ofratchet grooves; the cylinder being movable in a first directiontogether with the piston rod with the pawl engaged in the ratchet grooveand movable in a second direction opposite the first directionseparately from the piston rod.
 3. The multiple pipette according toclaim 2, wherein the piston rod is provided with an operation knob whichis movable for moving the piston rod separately from the cylinder; andthe operation knob being moved in the first direction for causing a gasin the liquid storing section to be discharged, the operation knob beingmoved in the second direction for causing a liquid to be drawn into theliquid storing section.
 4. The multiple pipette according to claim 3,wherein the first pipette incorporates a slide piece for supporting thepawl, the pawl being held on the slide piece when the piston rod ismoved by the operation knob.
 5. The multiple pipette according to claim1, wherein the first pipette includes a piston rod for pushing out theliquid from the liquid storing section, and a housing accommodating thepiston rod; the liquid storing section being defined by a syringe havingan inner space, the syringe being threadedly attached to the housing. 6.The multiple pipette according to claim 1, wherein the first pipetteincludes a nozzle connected to the liquid storing section, the nozzleincluding a dispensing orifice for dispensing the liquid from the liquidstoring section to the outside.
 7. The multiple pipette according toclaim 6, wherein the first pipette includes a cap removably attached forcovering the dispensing orifice.
 8. The multiple pipette according toclaim 6, wherein the nozzle is protected by a reinforcing portion.
 9. Amethod of using a multiple pipette which comprises a first pipette fordispensing a first liquid stored in a liquid storing sectiondivisionally a plurality of times each by a constant amount, and asecond pipette for dispensing a second liquid drawn from outside all ata time; the first liquid being a reference liquid containing a knownconcentration of a particular component, whereas the second liquid beinga sample liquid containing an unknown concentration of a particularcomponent.
 10. A method of using a multiple pipette which comprises afirst pipette for dispensing a first liquid stored in a liquid storingsection divisionally a plurality of times each by a constant amount, anda second pipette for dispensing a second liquid drawn from outside allat a time; the second liquid being mixed or diluted with the firstliquid.